This invention relates to a method for reducing pressure losses in a cyclone separator and a ducting system by preventing a particulate material from being deposited and heaped in the vicinity of a junction point between a duct and the cyclone separator to reduce pressure losses in the cyclone separator.
A cyclone separator is a device well-known in the art as a dust collecting system for separating and collecting a particulate material from a gas entraining the particulate material under a centrifugal force. With the cyclone separator, the gas is introduced into its funnel-shaped shell by means of a duct connected to the shell in a tangential direction to impart a gyratory motion to the gas to separate the particulate material from the gas.
The duct for introducing the gas into the cyclone separator has a horizontally extending section in the vicinity of a junction point to the funnel-shaped shell of the separator. The horizontally extending section is composed of a first horizontal portion having a width of the duct and a second horizontal portion extending narrowly from the first portion and connecting with the funnel-shaped shell in a tangential direction thereof. It is at the first and second portions that the particulate material tends to be deposited so as to disturb the flow of the introduced gas to thereby cause the increase of pressure losses in the cyclone separator. In this case, a sufficient gyratory motion of the gas is not produced in the inside of the cyclone separator, such that efficient separation of the particulate material from the gas cannot be achieved.
The conventional practice for preventing a particulate material from being deposited at the horizontally extending duct section has been to provide the duct section with a tilt to cause the material to slide thereon to prevent its deposition. More specifically, the horizontally extending duct section is inclined downwards towards its upstream side or, alternatively, towards the funnel-shaped shell of the cyclone separator. Still alternatively, the horizontally extending duct section has a portion inclined downwards towards its upstream side and a portion inclined downwards towards the funnel-shaped shell of the cyclone separator.
The above described conventional practice has, however, the following disadvantages. First of all, if the horizontally extending duct section is tilted downwards towards the upstream side of the duct, the particulate material descending on the inclined portion is kept there stationarily by the entering gas stream, unless the tilt is steep to some extent, with the result that the particulate material is deposited on the inclined duct section to disturb the introduced gas flow to thereby cause the increase of pressure losses in the cyclone separator. In addition, the particulate material continues to be deposited and, when reaching a certain amount or volume, the material can no longer be kept stationarily by the entering gas stream so that it collapses intermittently and slides down along the inclined section towards the upstream side of the duct. This also causes a gas flow to be disturbed, leading to increased pressure losses in the cyclone separator. If the horizontally extending duct section is inclined downwards towards the cyclone separator, the gas is introduced in the downward tangential direction into the inside of the shell of the cyclone separator so that the gas is directed towards a discharge duct provided at the bottom of the separator without a sufficient gyratory motion being imparted to the gas in the cyclone separator. As a result of insufficient separation of the gas and the particulate material in the shell of the cyclone separator, the separation efficiency of the cyclone separator is lowered. Finally, if the horizontally extending section has a portion inclined downwardly towards the upstream side of the duct and also a portion inclined downwardly towards the shell, the above described deficiencies are presented simultaneously. In addition, since the ordinary duct annexed to the cyclone separator is extended horizontally in the vicinity of the junction point to the shell, the remodelling construction work for imparting a tilt to the duct section is troublesome and also results in increased costs.